What ideas do you have for hosting a party prank that everyone knows about except one guest?

I just watched an episode of the Twilight Zone, and it was very interesting. This lady was at the bus station and she was checking in to get her ticket, and the ticket man told her he already gave her the ticket. He said the bus is still late, and she should stop bothering him every 15 minutes. The weird thing is that she never talked to this man before. Things like this kept happening as different people at the bus station would interact with her, and she started feeling like she was going crazy or delusional.

I thought it would be fun to host a party where everyone is acting a certain way, except for one guest who doesn't understand what is going on.

Can you help me think of some good ideas? For instance...

Everyone always goes to the bathroom in pairs, which would be weird since it is in my home.

or

The pizza man comes returns with more pizza of the exact same variety that was ordered the first time, and claiming that it was charged to somebody's credit card. We agree to sign for the pizza. Then the pizza man returns a third time with more of the same kind of pizza, and it explodes into a huge argument.

Any other ideas? Do you like my ideas, or do you want to make suggestions to make it more believable and interesting?